The relationship between sleep, pain,and musculoskeletal injuries in US Army Soldiers

The purpose of this study was to investigate the relationship between sleep and pain in military personnel and to determine if metrics of sleep and pain intensity differ between the injured and uninjured in this population.

Active-duty US Army Soldiers (n=308; 26.8±6.5 years, 82% male) from the 2nd Infantry Division, Joint Base Lewis-McChord, Washington, and 101st Airborne Division, Fort Campbell, Kentucky, completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and questionnaires about current musculoskeletal injuries and pain intensity (0=no pain to 10=worst imaginable pain). Pearson correlation coefficients were used to assess the association between pain and sleep. Differences in sleep and pain between injured and uninjured participants were determined using an analysis of covariance.

Pain intensity was positively correlated with sleep quality (global PSQI score, r=0.337, p<0.001) and daytime sleepiness (ESS score, r=0.163, p=0.005), and negatively associated with sleep duration (r=-0.118, p=0.039). Injured participants accounted for 37.7% (n=116) of the study population. Injured participants reported greater pain intensity (3.7±2.5 vs 1.3±1.9, p<0.001), were older (28.5±7.4 years vs 25.8±5.7 years, p=0.001) and in the service longer (6.3±6.3 years vs 4.6±4.7 years, p=0.013) than uninjured participants. Injured participants had higher global PSQI scores (9.0±4.1 vs 6.4±3.4, p<0.001), including each of the seven PSQI components (all p<0.050), and reported sleeping less per night than uninjured participants (5.7±1.3 hours vs 6.1±1.2 hours, p=0.026).

These data demonstrate that pain intensity is associated with sleep in active-duty US Army Soldiers and that those who report a musculoskeletal injury, regardless of age and time in service, report poorer sleep quality, shorter sleep durations, and greater levels of pain than uninjured Soldiers.